Laser pulse shaping for additive manufacturing

ABSTRACT

The present disclosure relates to an apparatus for additively manufacturing a product in a layer-by-layer sequence, wherein the product is formed using powder particles deposited on an interface layer of a substrate. A laser generates first and second beam components. The second beam component has a higher power level and a shorter duration than the first beam component. A mask creates a 2D optical pattern in which only select portions of the second beam components can irradiate the powder particles. The first beam component heats the powder particles close to a melting point, where the particles experience surface tension forces relative to the interface layer. While the particles are heated, the second beam component further heats the particles and also melts the interface layer before the surface tension forces can act on and distort the particles, enabling the particles and the interface layer are able to bond together.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/538,152, filed Aug. 12, 2019, and claims priority of U.S. patentapplication Ser. No. 15/010,107, filed Jan. 29, 2016, which is adivisional of U.S. patent application Ser. No. 15/010,107, filed Jan.29, 2016 (U.S. Pat. No. 10,376,987). Related disclosure is included inU.S. patent application Ser. No. 14/882,762 entitled “Spatter ReductionLaser Scanning Strategy In Selective Laser Melting”, filed Oct. 14, 2015(U.S. Pat. No. 10,220,471). The entire disclosures of each of the aboveapplications are incorporated herein by reference.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with Government support under Contract No.DE-AC52-07NA27344 awarded by the United States Department of Energy. TheGovernment has certain rights in the invention.

BACKGROUND Field of Endeavor

The present application relates to the art of melting powdered materialthrough laser pulse shaping, a technique which can be applied toadditive manufacturing to create three-dimensional parts.

State of Technology

This section provides background information related to the presentdisclosure which is not necessarily prior art.

U.S. Pat. No. 4,944,817 for multiple material systems for selective beamsintering issued Jul. 31, 1990 to David L. Bourell et al. and assignedto Board of Regents, The University of Texas System provides the stateof technology information reproduced below.

A method and apparatus for selectively sintering a layer of powder toproduce a part comprising a plurality of sintered layers. The apparatusincludes a computer controlling a laser to direct the laser energy ontothe powder to produce a sintered mass. The computer either determines oris programmed with the boundaries of the desired cross-sectional regionsof the part. For each cross-section, the aim of the laser beam isscanned over a layer of powder and the beam is switched on to sinteronly the powder within the boundaries of the cross-section. Powder isapplied and successive layers sintered until a completed part is formed.

U.S. Pat. No. 5,155,324 for a method for selective laser sintering withlayerwise cross-scanning issued Oct. 12, 1992 to Carl R. Deckard et al.,University of Texas at Austin, provides the state of technologyinformation reproduced below.

Selective laser sintering is a relatively new method for producing partsand other freeform solid articles in a layer-by-layer fashion. Thismethod forms such articles by the mechanism of sintering, which refersto a process by which particulates are made to form a solid mass throughthe application of external energy. According to selective lasersintering, the external energy is focused and controlled by controllingthe laser to sinter selected locations of a heat-fusible powder. Byperforming this process in layer-by-layer fashion, complex parts andfreeform solid articles which cannot be fabricated easily (if at all) bysubtractive methods such as machining can be quickly and accuratelyfabricated. Accordingly, this method is particularly beneficial in theproduction of prototype parts, and is particularly useful in thecustomized manufacture of such parts and articles in a unified mannerdirectly from computer-aided-design (CAD) orcomputer-aided-manufacturing (CAM) data bases.

Selective laser sintering is performed by depositing a layer of aheat-fusible powder onto a target surface; examples of the types ofpowders include metal powders, polymer powders such as wax that can besubsequently used in investment casting, ceramic powders, and plasticssuch as ABS plastic, polyvinyl chloride (PVC), polycarbonate and otherpolymers. Portions of the layer of powder corresponding to across-sectional layer of the part to be produced are exposed to afocused and directionally controlled energy beam, such as generated by alaser having its direction controlled by mirrors, under the control of acomputer. The portions of the powder exposed to the laser energy aresintered into a solid mass in the manner described hereinabove. Afterthe selected portions of the layer have been so sintered or bonded,another layer of powder is placed over the layer previously selectivelysintered, and the energy beam is directed to sinter portions of the newlayer according to the next cross-sectional layer of the part to beproduced. The sintering of each layer not only forms a solid mass withinthe layer, but also sinters each layer to previously sintered powderunderlying the newly sintered portion. In this manner, the selectivelaser sintering method builds a part in layer-wise fashion, withflexibility, accuracy, and speed of fabrication superior to conventionalmachining methods.

United States Published Patent Application No. 2014/0252687 for a systemand method for high power diode based additive manufacturing by BassemS. El-Dasher; Andrew Bayramian; James A. Demuth; Joseph C. Farmer; and;Sharon G. Torres; published Sep. 11, 2014 and assigned to LawrenceLivermore National Security, LLC provides the state of technologyinformation reproduced below.

A system is disclosed for performing an Additive Manufacturing (AM)fabrication process on a powdered material forming a substrate. Thesystem may make use of a diode array for generating an optical signalsufficient to melt a powdered material of the substrate. A mask may beused for preventing a first predetermined portion of the optical signalfrom reaching the substrate, while allowing a second predeterminedportion to reach the substrate. At least one processor may be used forcontrolling an output of the diode array.

SUMMARY

Features and advantages of the disclosed apparatus, systems, and methodswill become apparent from the following description. Applicant isproviding this description, which includes drawings and examples ofspecific embodiments, to give a broad representation of the apparatus,systems, and methods. Various changes and modifications within thespirit and scope of the application will become apparent to thoseskilled in the art from this description and by practice of theapparatus, systems, and methods. The scope of the apparatus, systems,and methods is not intended to be limited to the particular formsdisclosed and the application covers all modifications, equivalents, andalternatives falling within the spirit and scope of the apparatus,systems, and methods as defined by the claims.

The inventor's apparatus, methods, and systems utilizes one or morepulsed lasers to melt and allow to re-solidify areas of powderedmaterial by overcoming the kinetics of powder agglomeration through apulse shape consisting of a low intensity portion and a high intensityportion by melting the powder, and partially melting the substrate atthe interface surface between the powder and the substrate such thatboth the powder and the interface layer of the substrate have beenmelted before surface tension can take effect on the now molten powderparticles. Without the proper temporal pulse profile, the powderparticles would melt first, and then surface tension would pull themtogether into an unpatterned blob; however, by employing the inventor'sapparatus, powder particles and the interface layer of the basesubstrate are melted before surface tension can take any detrimentaleffects, allowing for successful printing.

This process can be applied for the purposes of additive manufacturing,and can also enable the printing of large patterned areas of powder insingle shot such as in Diode Additive Manufacturing (DiAM) and repeatingthe process to build up layers which constitute the part to bemanufactured. The current embodiment of this invention has shown theability in the laboratory to overcome the surface tension effects duringthe melting process and to create patterned images in a single lasershot.

Current powder bed fusion additive manufacturing systems (EOS, ConceptLaser, etc.) use one or more 100-1,000 W lasers to melt layers ofpowdered material by scanning the laser over the substrate, melting thepowder and bonding it to the base in a 2D pattern. A new layer of powderis then spread across the layer and a new arbitrary pattern is appliedto the powder using the laser. These lasers are typically continuouswave systems, and thus are scanned around the build platform with somespot size, power, and velocity that is material dependent in order toachieve the correct melt characteristics.

The inventor's apparatus, systems, and methods produce entire layers (ormacroscopic areas) in a single shot that are sub-patterned with hundredsto >millions of pixels. The inventor's apparatus, methods, and systemshave the potential to dramatically decrease the cost to producingadditively manufactured parts, enabling the move from prototyping/highvalue production to mass manufacturing.

One embodiment of the inventor's method for fusing large areas oflayered powder into solid material and bonding it to a substrateincludes the steps of providing a substrate, positioning a first layerof powder particles on said substrate producing a first interfacebetween said first layer of powder particles and said substrate,producing a first data file defining a planar cross section of the firstarea to be printed, providing one or more lasers that either can becombined to produce a temporally varying bonding pulsed laser beam,providing a mask such as an optically addressed light valve that istransparent to said portion of said bonding pulsed laser beam, where themask contains data from said first data file, and directing said bondingpulsed laser beam having a portion containing said first data file ontosaid first layer of powder particles on said substrate, melting saidfirst layer of powder particles and the said substrate at said interfaceto bond said first layer of powder particles to said substrate beforesurface tension can affect the printed image.

One embodiment of the inventor's additive manufacturing apparatus forfusing large areas of layered powder into solid material and bonding itto a substrate includes providing a substrate, positioning a first layerof powder particles on said substrate producing a first interfacebetween said first layer of powder particles and said substrate,producing a first data file defining a planar cross section of the firstarea to be printed, providing one or more lasers that either can becombined to produce a temporally varying bonding pulsed laser beam,providing a mask such as an optically addressed light valve that istransparent to said portion of said bonding pulsed laser beam, where themask contains data from said first data file, and directing said bondingpulsed laser beam having a portion containing said first data file ontosaid first layer of powder particles on said substrate melting saidfirst layer of powder particles and the said substrate at said interfaceto bond said first layer of powder particles to said substrate beforesurface tension can affect the printed image.

The inventor's apparatus, systems, and methods have a number ofadvantages. For example, they can perform laser printing of powder withmuch less spatter and produce more uniform melt. In the prior artsystems spatter landing on a freshly consolidated melt track can form anincomplete weld with that surface. This can prevent a uniform powderspreading on top of the consolidated melt track. The outcome can be thecreation of porosities, which is detrimental to the part quality.

The powder used in SLM is expensive. With the inventor's apparatus,systems, and methods spatter is minimized, the powder particledistribution will remain the same after multiple uses, hence, improvingthe re-use (recyclability) of the powder and minimizing waste.

Another advantage of the invention is to produce large macroscopic areasof fused material in a single shot. This has the ability to reducethermally induced stress concentrations, and to reduce thermal warpagewhen additively manufacturing parts. Furthermore, by patterning a largebeam for the purposes of additive manufacturing, the system is far morescalable than using a single point laser and scanning it to create theimage, and production rates can be increased virtually without limit.

In another aspect the present disclosure relates to an apparatus foradditively manufacturing a product in a layer-by-layer sequence, whereinthe product is formed using particles of powdered feedstock materialdeposited on an interface layer of a substrate. The apparatus maycomprise a laser system configured to generate a first beam componentproviding a first power flux level, and a second beam componentproviding a second power flux level which is greater than said firstpower flux level. A mask may be included which is disposed between thelaser system and the powdered feedstock material for creating a 2Doptical pattern in which first portions of the first and second beamcomponents are allowed to pass through the mask to irradiate thepowdered feedstock material, and second portions of the first and secondbeam components are not allowed to pass through to the powderedfeedstock material. The first beam component is operable to heat thepowdered feedstock material at least to substantially a melting point ofthe powdered feedstock material, at which point the particles ofpowdered feedstock material begin to experience surface tension forcesrelative to said interface layer of the substrate. While the particlesof powdered feedstock material are heated at least to substantially themelting point, the second beam component further heats the particles ofpowdered feedstock material and melts the interface layer of thesubstrate before the surface tension forces can act on the particles ofpowdered feedstock material to distort the particles of powderedfeedstock material, and such that the particles of powdered feedstockmaterial and the interface layer are able to bond together.

In another aspect the present disclosure relates to an apparatus foradditively manufacturing a product in a layer-by-layer sequence, whereinthe product is formed using particles of powdered feedstock materialdeposited on an interface layer of a substrate. The apparatus maycomprise a computer, a laser system controlled by the computer andconfigured to generate first and second beam components. The first beamcomponent provides a first power flux level through a laser pulse havinga millisecond duration, and the second beam component provides a secondpower flux level through a second laser pulse which has a second powerflux level greater than the first power flux level, but which has a timeduration which is shorter by at least an additional 1×10⁻³ factor thanmilliseconds. A dynamically controllable mask may be included which isdisposed between the laser system and the powdered feedstock material.The mask is controllable by the computer and is used for creating a 2Doptical pattern in which first portions of the first and second beamcomponents are allowed to pass through the mask to irradiate thepowdered feedstock material, and wherein second portions of the firstand second beam components are not allowed to pass through to thepowdered feedstock material. The first beam component is operable toheat the powdered feedstock material at least to substantially a meltingpoint of the powdered feedstock material, at which point the particlesof powdered feedstock material begin to experience surface tensionforces relative to said interface layer of the substrate. While theparticles of powdered feedstock material are heated at least tosubstantially the melting point, the second beam component operates tofurther heat the particles of powdered feedstock material and melts theinterface layer of the substrate before the surface tension forces canact on the particles of powdered feedstock material to distort theparticles of powdered feedstock material, and such that the particles ofpowdered feedstock material and the interface layer are able to bondtogether.

In still another aspect the present disclosure relates to an apparatusfor additively manufacturing a product in a layer-by-layer sequence,wherein the product is formed using particles of powdered feedstockmaterial deposited on an interface layer of a substrate. The apparatusmay comprise a computer and a laser system controlled by the computer.The laser system may be configured to generate a first beam componentusing laser diode which provides a first power flux level through alaser pulse having a millisecond duration. The laser system may furtherbe configured to generate a second beam component using a Q-switchedlaser which provides a second power flux level through a second laserpulse which has a second power flux level greater than the first powerflux level, but which has a time duration which is shorter by at leastan additional 1×10⁻³ factor than milliseconds. A dynamicallycontrollable mask may be included which is comprised of an opticallyaddressable light valve. The mask is disposed between the laser systemand the particles of powdered feedstock material, and which iscontrollable by the computer, for creating a 2D optical pattern in whichfirst portions of the first and second beam components are allowed topass through the mask to irradiate the particles of powdered feedstockmaterial, and second portions of the first and second beam componentsare not allowed to pass through to the particles of powdered feedstockmaterial. The first beam component is operable to heat the particles ofpowdered feedstock material at least to substantially a melting point ofthe particles of powdered feedstock material, at which point theparticles of powdered feedstock material begin to experience surfacetension forces relative to said interface layer of the substrate. Whilethe particles of powdered feedstock material are heated at least tosubstantially the melting point, the second beam component is operableto further heat the particles of powdered feedstock material and meltthe interface layer of the substrate before the surface tension forcescan act on the particles of powdered feedstock material to distort theparticles of powdered feedstock material, and such that the particles ofpowdered feedstock material and the interface layer are able to bondtogether.

The apparatus, systems, and methods are susceptible to modifications andalternative forms. Specific embodiments are shown by way of example. Itis to be understood that the apparatus, systems, and methods are notlimited to the particular forms disclosed. The apparatus, systems, andmethods cover all modifications, equivalents, and alternatives fallingwithin the spirit and scope of the application as defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of the specification, illustrate specific embodiments of theapparatus, systems, and methods and, together with the generaldescription given above, and the detailed description of the specificembodiments, serve to explain the principles of the apparatus, systems,and methods.

FIG. 1 illustrates a prior art additive manufacturing system.

FIG. 2A is a high level block diagram of an example of one embodiment ofa system in accordance with the present invention.

FIG. 2B illustrates an embodiment of the inventor's additivemanufacturing apparatus, systems, and methods from a spatialperspective.

FIG. 3 shows a first layer of powder particles applied to the substratewith an interface between the first layer of powder particles and thesubstrate.

FIG. 4 shows a bonding laser beam heating and melting the first layer ofpowder particles and melting the substrate at the interface between thefirst layer of powder particles and the substrate.

FIG. 5 shows a laser beam heating the first layer of now melted powderparticles to form the first layer of the product.

FIG. 6 shows a second layer of powder particles applied to the firstlayer of the product with an interface between the second layer ofpowder particles and the first solidified layer previously consisting ofpowder particles.

FIG. 7 shows a bonding laser beam heating and melting the second layerof powder particles and melting the first layer of the product at theinterface between the second layer of powder particles and the firstlayer of the product.

FIG. 8 shows a laser beam heating the second layer of now melted powderparticles to form the second layer of the product.

FIG. 9 is a graph illustrating an embodiment of the inventor's additivemanufacturing apparatus, systems, and methods from a temporalperspective.

FIG. 10 is a graph illustrating another embodiment of the inventor'sadditive manufacturing apparatus, systems, and methods from a temporalperspective.

FIG. 11 is a graph illustrating yet another embodiment of the inventor'sadditive manufacturing apparatus, systems, and methods from a temporalperspective.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring to the drawings, to the following detailed description, and toincorporated materials, detailed information about the apparatus,systems, and methods is provided including the description of specificembodiments. The detailed description serves to explain the principlesof the apparatus, systems, and methods. The apparatus, systems, andmethods are susceptible to modifications and alternative forms. Theapplication is not limited to the particular forms disclosed. Theapplication covers all modifications, equivalents, and alternativesfalling within the spirit and scope of the apparatus, systems, andmethods as defined by the claims.

Additive manufacturing is changing the way the world makes things. It ison brink of being able to increase to production rates relative to massmanufacturing, but is still currently stuck in theprototyping/high-value-only product creation phase. There are many typesof additive manufacturing, but one of the most precise systems that canhandle the widest variety of materials (plastics, ceramics, and metals)is powder bed fusion (also known as DMLS, SLS, SLM, etc. each companybrands it with their own name, but the common method description is allpowder bed fusion). Current powder bed fusion additive manufacturingsystems (EOS, Concept Laser, etc.) use 100-1,000 W fiber lasers(typically 1-4) to melt layers of powdered material by scanning thelaser over the substrate, melting the powder and bonding it to the basein a 2D pattern. A new layer of powder is the spread across the layerand a new arbitrary pattern is applied to the powder using the laser.These lasers are typically continuous wave systems, and thus are scannedaround the build platform with some spot size, power, and velocity thatis material dependent in order to achieve the correct meltcharacteristics.

The inventor's additive manufacturing system uses a temporally modulatedlaser beam to selectively fuse a layer of powder. One embodiment of thismethod is to produce a 3D printed part wherein the part comprises aplurality of fused layers. The system includes a computer controllingthe output of one or more lasers such that a time varying photon fluxilluminates the desired powder particles to successfully perform themelting operation, bonding the powder to the substrate beneath toproduce a fused mass.

One embodiment of the invention uses low cost diode lasers to produce alow intensity (containing kilowatts of power) photon flux component overlong duration (milliseconds), and a solid state pulsed (often referredto as Q-switched) Nd:YLF laser to produce a high intensity component(containing milli-Joules to Joules of energy) over a short duration(microseconds to nanoseconds). By delivering the majority of the energywith diode lasers, the bulk of the laser light can be generated using alow cost photon source. Utilizing the higher intensity pulsed laser todeliver the final burst of energy, surface tension forces are able to beovercome to successfully melt the powder and bond it to the layer below.

The embodiment used to reduce this invention to practice consisted of alow intensity fluence (LIF) of 5.6 kW generated by diode lasersilluminating an area of 5 mm by 5 mm. The high intensity fluence (HIF)of <1 Joule was generated by a solid state Q-switched Nd:YLF laserco-linear with the diode laser beam. An optically addressed light valve(a type of mask) was used to create a pattern in both the LIF and HIFbeams to create a 2D plane of melted metal in the desired pattern thatwas fused to the substrate below it. This fused mass includesconsolidated material produced by the laser energy that passes throughthe area of the mask that is transparent to the laser diode beams. Theportion of the fused mass that is left unconsolidated is that portionoutside of the laser energy that passes through the transparent area ofthe mask. The unconsolidated material is that area untouched by thediode beams. The unconsolidated material corresponds to the area of themask not transparent to the laser diode beam. The system utilizes anoptically addressed light valve (OALV) having first and secondcomponents. The first component represents the digital image of thefirst 2D layer and the second component represents the portion of thelight beam that is outside of the digital image of the first 2D layer.The two components are directed to the light valve system that acts as adynamic mask and allows the portion containing the digital image of thefirst 2D layer to pass while blocking the component that is outside ofthe digital image of the first 2D layer. In one embodiment, the maskcomprises a controllable liquid crystal polarization rotator comprisinga liquid crystal display (LCD) positioned upstream of a polarizingelement, relative to a direction of travel of the laser energy.

Referring now to the drawings, and in particular to FIG. 1 , a prior artadditive manufacturing system is illustrated. The prior art additivemanufacturing system is designated generally by the reference numeral100. A print head directs a projected beam 108 onto metal powderparticles 104 that have been deposited on a substrate 102. The printhead and projected beam 108 move according to a predetermined rasterpattern 110 that produces the consolidated mass of metal powderparticles 104 according to the digital image of the first 2D layer. Theprojected beam 108 solidifies the metal powder particles 104 accordingto the digital image of the first 2D layer information. The portion 106of the mass of metal powder particles outside of the consolidated massof metal powder particles 104 is designated as the unconsolidated massof metal powder particles 106.

Once the first layer of consolidated mass of metal powder particles 104is completed, production of the second layer of the product is started.A second layer of metal powder particles is applied on top of thecompleted first layer of metal powder particles 104. This procedure iscontinued by repeating the steps and building the final product in alayer by layer process.

Referring now to FIGS. 2A and 2B, an embodiment of the inventor'sadditive manufacturing apparatus, systems, and methods is illustrated.The embodiment is designated generally by the reference numeral 200. Theembodiment 200 utilizes a pulsed laser to overcome the kineticscondition by delivering a pulse of laser energy before the powder ismelted to allow it to bond to the base. Not only can the pulsed laserallow for the use of lower diode power fluxes, but it also allows forincredibly fine resolution to be achieved. Part resolution limits thatare based on thermal diffusion in the powder bed scale with the time theenergy is applied. The use of the solid state Q-switched laser providesnano-second time scales and can generate nano-meter scale resolution.The embodiment 200 uses a diode pulse in milliseconds, followed by ashort pulse from the Q-switched laser in nanoseconds. The embodiment 200includes the components listed and described below.

-   -   Substrate 202.    -   First powder particles layer 204.    -   Unconsolidated material 206.    -   Selective area mask 208.    -   Optically addressed light valve (OALV) 210/212.    -   Area of Mask transparent to laser diode beams 210.    -   Area of Mask not transparent to laser diode beams 212.    -   Diode array and Q-switched laser 214.    -   Diode and Q-switched laser beam producing laser energy 216.

The embodiment 200 is an additive manufacturing system for selectivelyfusing a layer of powder to produce a part wherein the part comprises aplurality of fused layers. The system includes a computer controlling alaser diode array and Q-switched laser 214 to direct the laser energy216 onto powder in the powder bed to produce a fused mass. The fusedmass includes consolidated material made from the first powder particles204, which is produced by the laser energy 216 that passes through thearea 210 of the mask that is transparent to the laser energy 216. Theportion of the fused mass that is left as unconsolidated material 206 isthat portion outside of the laser energy 216 that passes through thearea 210 of the mask. The unconsolidated material 206 is that areauntouched by the laser energy 216. The unconsolidated material 206corresponds to the area 212 of the mask not transparent to laser energy216. The embodiment 200 utilizes pulses from the diode array andQ-switched laser 214 to produce the laser energy 216 that is deliveredbefore the powder is melted to allow it to bond to the base.

The computer controller performs various operations of the system 200.Initially a 3D model of the desired product is designed by any suitablemethod, e.g., by bit mapping or by computer aided design (CAD) softwareat a PC/controller. The CAD model of the desired product iselectronically sliced into series of 2-dimensional data files, i.e., 2Dlayers, each defining a planar cross section through the model of thedesired product. The 2-dimensional data files are stored in a computerand provide a digital image of the final product.

The digital images are used in the additive manufacturing system 200 toproduce the final product. Solidified powder particles are applied to asubstrate in a layer by layer process to produce the final product. Thedigital image of the first 2D layer is used to produce the first layerof the desired product. The digital image of the first 2D layer is usedto create a mask that only allows the desired portion of the laser beamto pass through the optically addressed light valve (OALV).

A delivery system directs metal powder particles onto substrate 202. Thesystem 200 utilizes a pulse or pulses from the diode array andQ-switched laser 214 to produce a pulsed diode beam, and then later aQ-switched laser beam, creating the laser energy 216 that is deliveredbefore the powder is fully melted by the diode lasers such that thefirst layer of powder particles and the first layer of the substrate 202melt, and are bonded together. Additional layers of powder are thenadded onto the first layer and the process is repeated.

The system's computer either determines or is programmed with theboundaries of the desired cross-sectional regions of the part. For eachcross-section, laser diode beam and Q-switched laser energy 216 isarranged to be projected onto a layer of powder particles and the laserenergy 216 is switched on to fuse only the powder within the boundariesof the cross-section 204. Powder particles are applied and successivelayers fused until a completed part is formed.

The system utilizes a light valve system (Optically addressed lightvalve (OALV) 210/212) producing the area 210 of the mask that istransparent to the laser energy 216 and producing the area 212 of themask that rejects the laser energy 216.

The light valve system provides first and second components. The firstcomponent is reprinted by laser energy 216, which represents the digitalimage of the first 2D layer, and the second component is the area 212,which represents the portion of the light beam that is outside of thedigital image of the first 2D layer. The two components are directed tothe light valve system that acts as a dynamic mask and allows theportion containing the digital image of the first 2D layer to pass whilerejecting the component that is outside of the digital image of thefirst 2D layer. Additional details of patterning high energy lasers, andthe light valve system are provided in a co-pending patent applicationpublished as U.S. Published Patent Application No. 2014/0252687 forSystem and Method For High Power Diode Based Additive Manufacturing. Thedisclosure of U.S. Published Patent Application No. 2014/0252687 isincorporated herein by this reference.

The first layer 204 of powder particles is bonded to the substrate 202by a bonding pulsed laser beam 216 (containing both diode laser andQ-switched laser beams) heating and melting the first layer 204 ofpowder particles and the substrate at the interface between the firstlayer 204 of powder particles and the substrate 202.

A diode laser creates the beam that generates the laser energy 216,which is incident on the light valve system 208 where the image to beprinted is imbedded in the beam. The first 2D layer is then projectedfrom the light valve system onto the layer 204 of metal powder particlesthat has been deposited on the substrate 202. The projected diode laserbeam, using the laser energy 216, heats up the metal powder particles ina pattern according to the digital image of the first 2D layerinformation, bringing the patterned image up close to the melting pointof the powdered material.

A q-switched pulsed laser beam provides energy to help form laser energy216, and is incident on the light valve system 208 where the image to beprinted is imbedded in the beam. The first 2D layer is then projectedfrom the light valve system onto the layer 204 of metal powder particlesthat has been deposited on the substrate 202. The projected q-switchedlaser beam provides the remaining energy required to melt the metalpowder particles and the interface layer of the substrate 202 in apattern according to the digital image of the first 2D layerinformation, melting the powder forming the patterned image and thesubstrate below it.

Once the first layer 204 is completed, production of the second layer ofthe product is started. A second layer of metal powder particles isapplied on top of the competed first layer 204. The second layer ofpowder particles is bonded to the first layer 204 of the product by abonding pulsed laser beam heating and melting the second layer of powderparticles and melting the first layer 204 at the interface between thesecond layer of powder particles and the first layer 204.

The inventor's apparatus, systems, and methods utilize time dependentshaping of the laser pulse to overcome a kinetics barrier in the physicsof powder melting in order to bond the powder to the base. Oneembodiment of the invention is as used in the additive manufacturingprocesses to construct nearly any material that can be melted and somethat cannot (like some ceramics) but that the heating process allowsthem to fuse. The pulsed laser can deliver the required energy eitherbefore, during, or after powder melting, but in all cases before thesurface tension forces of the molten powder can distort the printedimage by pulling the molten powder together to lower the total surfaceenergy. The additive manufacturing system begins with a layer of powderbeing spread across the substrate. As illustrated in FIG. 3 , the firstlayer of powder particles 204 are applied to substrate 202. The inventorfound that the condition existed where the powder particles 204 wouldmelt and ball up but not bond to the substrate 202 if the laser flux wasnot high enough. The inventor discovered that by using a correctlyshaped pulsed laser beam, the effect of surface tension forces on themolten particles could be overcome by delivering an additional pulse oflaser energy before the powder particles 204 were fully melted to allowthe powder particles 204 to be melted at the interface between theparticles and substrate thereby bonding the particles 204 to thesubstrate 202.

Referring now to FIG. 4 , a pulsed diode laser beam 216 a is shownheating and melting the first layer of powder particles 204, but notmelting the substrate 202 at interface 218.

Referring now to FIG. 5 an additional q-switched pulsed laser beam 224with ns duration containing MW of power, is shown heating the firstlayer of powder particles and delivering sufficient energy to melt thefirst layer of powder particles and the interface layer 218 of FIG. 4such that the melted particles adhere to the substrate layer 202 to formthe first layer 204 of the product that has been bonded to the substrate202.

Once the first layer 204 is completed production of the second layer ofthe product is started. As illustrated in FIG. 6 , a second layer ofpowder particles 220 are applied to the first layer 204 of the productwith an interface between the second layer of powder particles 220 andthe first layer 204 of the product.

Referring now to FIG. 7 , the pulsed diode laser beam 216 a is shownheating and melting the second layer of powder particles 220, but notmelting the first layer 204 at interface 218.

Referring now to FIG. 8 , the additional q-switched pulsed laser beam224 with ns duration containing MW of power, is shown heating the firstlayer 204 of powder particles and delivering sufficient energy to meltthe first layer of powder particles and the interface layer 218 of FIG.7 such that the melted particles adhere to the first layer 204 to formthe first layer 220 of the product that has been bonded to the substrate202.

The inventors' apparatus, systems, and methods provide an additivemanufacturing pulsed laser that enables the printing of large areas ofpowder in single shot either by itself or in conjunction with anotherlaser, overcoming the kinetics of powder agglomeration by shaping of thelaser pulse enabling melting of the base substrate before surfacetension can take effect. The system utilizes a mask such as an opticallyaddressed light valve (OALV) having first mask and second maskcomponents. The fused mass includes consolidated material produced bythe laser energy that passes through the first mask component area ofthe mask that is transparent to the laser diode beams. The portion ofthe fused mass that is left unconsolidated is that outside of the laserenergy that passes through the second mask component area of the mask.

Referring now to FIG. 9 a graph illustrates an embodiment of theinventor's additive manufacturing apparatus, systems, and methods. Thegraph is designated generally by the reference numeral 900. Theinventor's additive manufacturing apparatus, systems, and methods use atemporally modulated laser beam to selectively fuse a layer of powder.The graph 900 illustrates the inventors' system from a temporalperspective where the pulses in superposition are synced at their endpoints.

Referring now to FIG. 10 a graph illustrates another embodiment of theinventor's additive manufacturing apparatus, systems, and methods. Thegraph is designated generally by the reference numeral 1000. Theinventor's additive manufacturing apparatus, systems, and methods use atemporally modulated laser beam to selectively fuse a layer of powder.The graph 1000 illustrates the inventors' system from a temporalperspective where the pulses in superposition are overlapped.

Referring now to FIG. 11 a graph illustrates yet another embodiment ofthe inventor's additive manufacturing apparatus, systems, and methods.The graph is designated generally by the reference numeral 1100. Theinventor's additive manufacturing apparatus, systems, and methods use atemporally modulated laser beam to selectively fuse a layer of powder.The graph 1100 illustrates the inventors' system from a temporalperspective where the pulses in superposition are non-overlapped.

Although the description above contains many details and specifics,these should not be construed as limiting the scope of the applicationbut as merely providing illustrations of some of the presently preferredembodiments of the apparatus, systems, and methods. Otherimplementations, enhancements and variations can be made based on whatis described and illustrated in this patent document. The features ofthe embodiments described herein may be combined in all possiblecombinations of methods, apparatus, modules, systems, and computerprogram products. Certain features that are described in this patentdocument in the context of separate embodiments can also be implementedin combination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination. Similarly, whileoperations are depicted in the drawings in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results.Moreover, the separation of various system components in the embodimentsdescribed above should not be understood as requiring such separation inall embodiments.

Therefore, it will be appreciated that the scope of the presentapplication fully encompasses other embodiments which may become obviousto those skilled in the art. In the claims, reference to an element inthe singular is not intended to mean “one and only one” unlessexplicitly so stated, but rather “one or more.” All structural andfunctional equivalents to the elements of the above-described preferredembodiment that are known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the present claims. Moreover, it is not necessary for adevice to address each and every problem sought to be solved by thepresent apparatus, systems, and methods, for it to be encompassed by thepresent claims. Furthermore, no element or component in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element or component is explicitly recited in the claims. Noclaim element herein is to be construed under the provisions of 35U.S.C. 112, sixth paragraph, unless the element is expressly recitedusing the phrase “means for.”

While the apparatus, systems, and methods may be susceptible to variousmodifications and alternative forms, specific embodiments have beenshown by way of example in the drawings and have been described indetail herein. However, it should be understood that the application isnot intended to be limited to the particular forms disclosed. Rather,the application is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the application asdefined by the following appended claims.

What is claimed is:
 1. An apparatus for additively manufacturing aproduct in a layer-by-layer sequence, wherein the product is formedusing particles of powdered feedstock material deposited on an interfacelayer of a substrate, the apparatus comprising: a laser systemconfigured to generate: a first beam component providing a first powerflux level; a second beam component providing a second power flux levelwhich is greater than said first power flux level; the first beamcomponent being operable to heat the powdered feedstock material to afirst level short of a melting point of the powdered feedstock material,at which point the particles of powdered feedstock material begin toexperience surface tension forces relative to said interface layer ofthe substrate, wherein the interface layer forms only an upper surfaceportion of the substrate; and after the particles of powdered feedstockmaterial are heated to the first level short of the melting point, thesecond beam component being operable to further heat the particles ofpowdered feedstock material to a second level to melt the particles ofpowdered feedstock material and also to melt the interface layer of thesubstrate before the surface tension forces can act on the particles ofpowdered feedstock material to distort the particles of powderedfeedstock material, wherein the interface layer of the substratecomprises a layer having a thickness less than a full thickness of thesubstrate, such that a portion of the interface layer remains unmeltedby the second beam component as the particles of powdered feedstockmaterial and the interface layer are bonded together; and the laserfurther being configured such that the second beam component has aduration less than the first beam component by a factor of at least1×10⁻³, and a power controlled to be sufficient only to melt theinterface layer of the substrate.
 2. The apparatus of claim 1, whereinthe first and second beam components comprise temporally varying laserbeam pulses.
 3. The apparatus of claim 1, wherein the laser systemincludes a diode laser array for generating the first beam component. 4.The apparatus of claim 1, wherein the laser system includes a pulsedsolid state laser for generating the second beam component.
 5. Theapparatus of claim 1, wherein: the laser system includes a laser diodearray configured to generate the first beam component, wherein the firstbeam component forms a first laser pulse having a duration ofmilliseconds; and the laser system includes a pulsed laser configured togenerate the second beam component, wherein the second beam componentforms a second laser pulse.
 6. The apparatus of claim 5, wherein: thefirst beam component has a power level on an order of kilowatts; and thebeam component has a power level on an order of milli-Joules to Joulesof energy.
 7. The apparatus of claim 1, further comprising a maskdisposed between the laser system and the powdered feedstock materialfor irradiating the feedstock material with a 2D optical pattern usingthe first and second beam components.
 8. The apparatus of claim 7,wherein the mask enables first portions of the first and second beamcomponents to pass through the mask to irradiate the powdered feedstockmaterial, and second portions of the first and second beam componentsare not allowed to pass through to the powdered feedstock material. 9.The apparatus of claim 8, wherein the mask comprises a digitallycontrollable mask.
 10. The apparatus of claim 7, further comprising acomputer for controlling the mask.
 11. The apparatus of claim 10,wherein the computer is configured to use 2D data files for controllingthe mask to construct each layer of the product.
 12. The apparatus ofclaim 8, wherein the mask comprises a dynamically controllable,optically addressable light valve enabling selected portions of thefirst and second beam components to pass therethrough to reach theparticles of powdered feedstock material, while preventing non-selectedportions of the first and second beam components from reaching theparticles of powdered feedstock material.
 13. The apparatus of claim 10,wherein the computer is configured to control the laser system such thatthe second beam component is applied after the first beam component hasheated the particles of powdered feedstock material to the first levelshort of the melting point.
 14. The apparatus of claim 7, wherein thecomputer is configured to control the laser system such that the secondbeam component is applied while the first beam component is still beingused to heat the particles of powdered feedstock material to the firstlevel short of the melting point.
 15. The apparatus of claim 1, furthercomprising a static mask interposed between the laser system and thepowdered feedstock material, for patterning the first and second beamcomponents on the powdered feedstock material.
 16. An apparatus foradditively manufacturing a product in a layer-by-layer sequence, whereinthe product is formed using particles of powdered feedstock materialdeposited on an interface layer of a substrate, the apparatuscomprising: a laser system including a diode laser array and a solidstate Q-switched laser, and being configured to generate: a first beamcomponent, using the diode laser array, providing a first power fluxlevel through a first laser pulse having a millisecond duration; asecond beam component, using the solid state Q-switched laser, providinga second power flux level through a second laser pulse which has asecond power flux level greater than said first power flux level, butwhich has a time duration on a nanosecond level and a resolution on ananometer scale; the first beam component being operable to heat theparticles of powdered feedstock material at least to a first level shortof a melting point of the particles of powdered feedstock material, atwhich point the particles of powdered feedstock material begin toexperience surface tension forces relative to said interface layer ofthe substrate, wherein the interface layer forms only an upper surfaceportion of the substrate; and while the particles of powdered feedstockmaterial are heated at least to the first level short of the meltingpoint, the second beam component being operable to further heat theparticles of powdered feedstock material and melt both the particles ofpowdered feedstock material and the interface layer of the substratebefore the surface tension forces can act on the particles of powderedfeedstock material to distort the particles of powdered feedstockmaterial, and such that the particles of powdered feedstock material andthe interface layer are able to bond together, and while a portion ofthe interface layer is not melted by the second beam component.
 17. Theapparatus of claim 16, wherein: the first power flux level of the firstbeam component is in kilowatts; and the second power flux level of thesecond beam component is in milli-Joules or Joules of energy.
 18. Theapparatus of claim 16, wherein the laser system is configured such thatat least one of the following conditions is applied: the second beamcomponent is applied after the first beam component has heated theparticles of powdered feedstock to the first level short of the meltingpoint, and immediately after the first beam component has been removed;or the second beam component is applied a predetermined time intervalafter the first beam component has heated the particles of powderedfeedstock material to the first level short of the melting point, andthe first beam component has been removed; or the second beam componentis applied while the first beam component is still being applied to heatthe particles of powdered feedstock material at least to substantially amelting point.
 19. An apparatus for additively manufacturing a productin a layer-by-layer sequence, wherein the product is formed usingparticles of powdered feedstock material deposited on an interface layerof a substrate, the apparatus comprising: a computer; a cad modelincluding a plurality of two dimensional data files for forming theproduce in a layer-by-layer operation; a laser system controlled by thecomputer and having: a diode laser array configured to generate a firstbeam component, the first beam component providing a first power fluxlevel having a millisecond duration; a solid state Q-switched laserconfigured to generate a second beam component, the second beamcomponent having a second power flux level greater than said first powerflux level, but which has a time duration which is shorter by at leastan additional 1×10⁻³ factor than milliseconds, and which providesnanometer scale resolution; the first beam component being operable toheat the particles of powdered feedstock material to a first level shortof a melting point, at which point the particles of powdered feedstockmaterial begin to experience surface tension forces relative to saidinterface layer of the substrate, wherein the interface layer forms onlyan upper surface portion of the substrate; and while the particles ofpowdered feedstock material are heated to the first level short of themelting point, the second beam component further heats the particles ofpowdered feedstock material to a second level and melts both theparticles of powdered feedstock material and the interface layer of thesubstrate before the surface tension forces can act on the particles ofpowdered feedstock material to distort the particles of powderedfeedstock material, and wherein the first and second beam componentsleave a portion of the substrate unmelted, and such that the particlesof powdered feedstock material and the interface layer are able to bondtogether.
 20. An apparatus for additively manufacturing a product in alayer-by-layer sequence, wherein the product is formed using particlesof powdered feedstock material deposited on an interface layer of asubstrate, the apparatus comprising: a laser system configured togenerate: a first beam component providing a first power flux level; asecond beam component providing a second power flux level which isgreater than said first power flux level; the first beam component beingoperable to heat the powdered feedstock material to a first level shortof a melting point of the powdered feedstock material, at which pointthe particles of powdered feedstock material begin to experience surfacetension forces relative to said interface layer of the substrate,wherein the interface layer forms only an upper surface portion of thesubstrate; and after the particles of powdered feedstock material areheated to the first level short of the melting point, the second beamcomponent being operable to further heat the particles of powderedfeedstock material to a second level to melt the particles of powderedfeedstock material and also to melt the interface layer of the substratebefore the surface tension forces can act on the particles of powderedfeedstock material to distort the particles of powdered feedstockmaterial, wherein the interface layer of the substrate comprises a layerhaving a thickness less than a full thickness of the substrate, suchthat a portion of the interface layer remains unmelted by the secondbeam component as the particles of powdered feedstock material and theinterface layer are bonded together; the laser further being configuredsuch that the second beam component has a duration less than the firstbeam component, and a power controlled to be sufficient only to melt theinterface layer of the substrate; the laser system including: a laserdiode array configured to generate the first beam component, the firstbeam component forming a first laser pulse having a first duration and apower level on an order of kilowatts; and a pulsed laser configured togenerate the second beam component, wherein the second beam componentforms a second laser pulse having a second duration which is less thanthe first duration, and wherein the second duration is in nanoseconds orless, and a power level of the second beam component is on an order ofmilli-Joules to Joules of energy.